Handheld volumetric ultrasound scanning device

ABSTRACT

An apparatus and related methods for ultrasonically scanning a tissue volume are described, the apparatus being particularly advantageous in the context of freehand ultrasound assisted biopsy of the breast although readily applied to non-biopsy contexts and other body parts. The apparatus comprises a casing configured and dimensioned for single-handed manipulation relative to a surface of the tissue, and a texturably couplant-porous material sheet extending across an opening of the casing. The texturably couplant-porous material sheet has an outer side and an inner side relative to the casing, the outer side for compressively contacting the tissue surface. The apparatus further comprises an ultrasound transducer positioned against the inner side of the texturably couplant-porous material sheet and being mechanically translatable thereacross for volumetrically scanning the tissue volume therethrough.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit of U.S. Provisional Ser. No.61/081,204, filed Jul. 16, 2008. This patent application is acontinuation-in-part of U.S. Ser. No. 11/757,996, filed Jun. 4, 2007,which claims the benefit of U.S. Ser. No. 60/803,762, filed Jun. 2, 2006and which published as US2007/028221A1 on Dec. 6, 2007. This patentapplication is also a continuation-in-part of PCT/US2007/010753, filedMay 2, 2007, which claims the benefit of U.S. Ser. No. 60/746,259, filedMay 2, 2006 and which published as WO2007/130526A2 on Nov. 15, 2007.Each of the above-referenced applications is incorporated by referenceherein.

FIELD

This patent specification relates to the ultrasonic imaging ofbiological tissues. More particularly, this patent specification relatesto a handheld volumetric ultrasound scanning device that, althoughadvantageously usable in other applications as well, is particularlyadvantageous for use in image-guided freehand biopsy procedures.

BACKGROUND AND SUMMARY

Biopsy refers generally to the removal of a tissue sample from a livingbody for examination. In the field of breast cancer detection andtreatment, breast tissue biopsies are often required when a suspiciouslesion has been detected. Alternatives to traditional open surgicalbiopsy have been developed that are less invasive and, therefore, lessrisky and less costly. Percutaneous breast biopsy refers to the use of abiopsy needle or other instrument, usually long and relatively narrow,to puncture through the skin and capture cellular tissue associated witha breast lesion. The captured tissue is removed from the body andexamined for a determination of whether the breast lesion represents abenign or malignant condition.

Percutaneous breast biopsy procedures include fine needle aspiration,core needle biopsy, and vacuum-assisted biopsy. In fine needleaspiration, a fine gauge needle (22 or 25 gauge) and a syringe are usedto sample fluid from a breast cyst or remove clusters of cells from asolid mass. In core needle biopsy, small samples of tissue are removedusing a hollow “core” needle. In vacuum-assisted biopsy, a specialbiopsy probe is inserted through a small opening in the skin. Unlikecore needle biopsy, which requires several separate needle insertions toacquire multiple samples, the special biopsy probe used duringvacuum-assisted biopsy is inserted only once for obtaining multiplesamples. Vacuum-assisted biopsy is often referenced by the brand name ofthe biopsy instrument used, such as MAMMOTOME® from Johnson & JohnsonEthicon Endo-Surgery, MIBB® (Minimally Invasive Breast Biopsy) from TycoInternational, Intact™ Breast Lesion Excision System from Intact MedicalSystems, and Celero™ from Suros, a Hologic Company.

As used herein, the terms radiologist, physician, surgeon, clinician,and so forth are used interchangeably and generically to refer tomedical professionals that analyze medical images and make clinicaldeterminations therefrom, and/or that perform medical procedures underthe at least partial guidance of medical imaging systems, it beingunderstood that such person might be titled differently, or might havediffering qualifications, depending on the country or locality of theirparticular medical environment. Percutaneous breast biopsy proceduresare often performed with the assistance of ultrasound imaging tofacilitate guidance of the biopsy instrument toward and into the breastlesion under study. In so-called freehand ultrasound assisted biopsy,the clinician holds an ultrasound transducer, typically a linear arraytransducer, against the skin with one hand while manipulating the biopsyinstrument with the other hand, the clinician watching the biopsyinstrument in real-time on the ultrasound monitor to help guide it tothe lesion. In such applications, it is necessary to keep the biopsyneedle positioned within the imaged plane in order for it to remainvisible on the ultrasound monitor during the procedure.

For the highly skilled clinician, freehand ultrasound assisted biopsy ofthe breast using a linear array ultrasound transducer can be quicklyperformed in an out-patient environment, and is much less expensive thanother breast biopsy procedures such as x-ray guided stereotactic biopsyand surgical biopsy. Although freehand ultrasound guided biopsy hasbecome a highly popular procedure, it could become even more popular ifit were easier to perform. Difficulties begin with the breast surfaceitself, which can be shifty beneath the linear array ultrasoundtransducer and even more so because of the slipperiness of theultrasound gel. The clinician needs to manipulate the linear arrayultrasound transducer in one hand and the biopsy needle in the otherhand such that the biopsy needle, which can be relatively thin(approximately 1 mm in diameter), is maintained along with the breastlesion within the scan plane of the linear array ultrasound transducerto allow the biopsy needle and lesion to be visible on the ultrasounddisplay. Moreover, the ultrasound display itself is often about threefeet away from the breast and difficult to view simultaneouslytherewith.

It would be desirable to facilitate a freehand ultrasound assistedbreast biopsy in a manner that improves one or more of image quality,thoroughness, patient comfort, sample quality, quickness of the process,and accessibility of the process to a wider range of clinicians ofdifferent skill levels. It is to be appreciated, however, that while oneor more of the preferred embodiments described herein is particularlyadvantageous for facilitating freehand ultrasound assisted breastbiopsy, there is ready applicability to a wide variety of medicalimaging applications in which real-time three-dimensional ultrasoundscanning is desirable such as, but not limited to, cardiac imaging andfetal imaging, both inside and outside the context of biopsy instrumentguidance. Other issues arise as would be readily apparent to one skilledin the art in view of the present disclosure.

According to one preferred embodiment, provided is an apparatus forultrasonically scanning a tissue volume having a tissue surface. Theapparatus comprises a casing configured and dimensioned forsingle-handed manipulation relative to the tissue surface, and atexturably couplant-porous material sheet extending across an opening ofthe casing. The texturably couplant-porous material sheet has an outerside and an inner side relative to the casing, the outer side forcompressively contacting the tissue surface. The apparatus furthercomprises an ultrasound transducer positioned against the inner side ofthe texturably couplant-porous material sheet and being mechanicallytranslatable thereacross for volumetrically scanning the tissue volumetherethrough. The incorporation of a texturably couplant-porous materialsheet, which can comprise for example a taut fabric sheet or a ventedmembrane, advantageously tends to at least partially stabilize thetissue surface as the ultrasound transducer is swept thereacross, whilealso providing for high quality in the images derived from thevolumetric ultrasound scans.

According to another preferred embodiment, provided is a method forperforming percutaneous biopsy of a target lesion in a tissue volume,comprising manually maintaining a handheld ultrasound probe incompressive contact with a surface of the tissue volume, the handheldultrasound probe comprising a texturably couplant-porous material sheethaving a first side compressively contacting the surface and a secondside opposite the first side, the handheld ultrasound probe furthercomprising an ultrasound transducer repetitively translated across thesecond side of the texturably couplant-porous material sheet to acquirevolumetric ultrasound scans of the tissue volume therethrough. Themethod further comprises viewing ultrasound images of the target lesionand at least a portion of a freehand percutaneous biopsy instrument onan ultrasound display that is updated in real time with the acquisitionof the volumetric ultrasound scans, and guiding the freehandpercutaneous biopsy instrument toward the lesion based at least in parton the viewed ultrasound images.

According to another preferred embodiment, provided is an apparatus forultrasonically scanning a tissue volume, comprising a processor and ahandheld ultrasound device. The handheld ultrasound device comprises acasing configured and dimensioned for single-handed manipulation and amechanically oscillated ultrasound transducer disposed therewithin. Thecasing has a top surface and a bottom opening. The handheld ultrasounddevice further comprises a membranous material sheet extending acrossthe bottom opening for compressively contacting a surface of the tissuevolume, the ultrasound transducer being mechanically translated acrossthe material sheet while in contact therewith, the ultrasound transduceracquiring ultrasonic scans of the tissue volume downward through thematerial sheet during the mechanical translation. The processorprocesses the ultrasonic scans to generate an ultrasound volumerepresentative of an ultrasonic property of the tissue volume. Thehandheld ultrasound device further comprises a first ultrasound displayintegral with an upper surface of the casing for displaying a firsttwo-dimensional image derived from the ultrasound volume, and a lidhingably coupled to the casing near the first ultrasound display, thelid being manually closable to cover the first display and manuallyopenable to uncover the first display and remain at a user-adjustableopening angle relative thereto. The handheld ultrasound device furthercomprises a second ultrasound display integral with an inner surface ofthe lid for displaying a second two-dimensional image derived from theultrasound volume when the lid is in an open position. The handheldultrasound device further comprises an angle detection device fordetecting the opening angle of the lid. Preferably, the processorcomputes the first two-dimensional image by compositing the ultrasoundvolume in a generally upward direction, and computes the secondtwo-dimensional image by receiving the detected opening angle andcompositing the ultrasound volume in a first direction faced by thesecond ultrasound display as determined by the detected opening angle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a perspective view of a handheld ultrasound scanningapparatus according to a preferred embodiment facilitating freehandultrasound assisted biopsy according to a preferred embodiment;

FIG. 1B illustrates an exploded perspective view of the handheldultrasound scanning apparatus of FIG. 1A;

FIGS. 2A and 2B illustrate side and front views, respectively, of thehandheld ultrasound scanning apparatus of FIGS. 1A and 1B facilitatingfreehand ultrasound assisted biopsy according to a preferred embodiment;

FIG. 3 illustrates a perspective view of a handheld ultrasound scanningapparatus according to a preferred embodiment;

FIG. 4 illustrates a perspective view of a handheld ultrasound scanningapparatus according to a preferred embodiment;

FIGS. 5A and 5B illustrate side and front views, respectively, of ahandheld ultrasound scanning apparatus according to a preferredembodiment;

FIG. 5C illustrates a top view of the handheld ultrasound scanningapparatus of FIGS. 5A-5B facilitating freehand ultrasound assistedbiopsy according to a preferred embodiment;

FIG. 5D illustrates a perspective view of the handheld ultrasoundscanning apparatus of FIGS. 5A-5B facilitating freehand ultrasoundassisted biopsy according to a preferred embodiment;

FIGS. 6A and 6B illustrate side and front views, respectively, of ahandheld ultrasound scanning apparatus according to a preferredembodiment;

FIG. 6C illustrates a perspective view of the handheld ultrasoundscanning apparatus of FIGS. 6A-6B facilitating freehand ultrasoundassisted biopsy according to a preferred embodiment;

FIG. 7 illustrates a side view of a handheld ultrasound scanningapparatus according to a preferred embodiment; and

FIG. 8 illustrates a top view of a handheld ultrasound scanningapparatus according to a preferred embodiment.

DETAILED DESCRIPTION

FIG. 1A illustrates a perspective view of a handheld ultrasound scanningapparatus 102 according to a preferred embodiment facilitating freehandultrasound assisted biopsy according to a preferred embodiment, a tissuephantom 106 representing the breast of a supine patient. FIG. 1Billustrates an exploded perspective view of the handheld ultrasoundscanning apparatus 102. It is to be appreciated that although freehandultrasound-assisted breast biopsy represents a particularly advantageoususe of the handheld ultrasound scanning apparatus 102, and although thehandheld ultrasound scanning apparatus 102 is further describedhereinbelow in the particular context of freehand ultrasound-assistedbreast biopsy, there are many other volumetric ultrasound imagingapplications that are within the scope of the preferred embodiments,including freehand ultrasound-assisted biopsy of other body parts, andincluding volumetric ultrasound imaging in non-biopsy contexts for thebreast and/or other body parts. Also illustrated in FIG. 1A is a biopsyinstrument 104 that may be used in conjunction with the handheldultrasound scanning apparatus 102 according to a preferred embodiment.Although shown as a needle-type biopsy instrument in the example of FIG.1A, it is to be appreciated that the biopsy instrument 104 can generallybe any of a variety of different surgical instruments for whichultrasound-assisted visualization is desired including, but not limitedto, fine needle aspiration instruments, core needle biopsy instruments,and vacuum-assisted biopsy instruments.

Handheld ultrasound scanning apparatus 102 comprises a casing 107 thatis configured and dimensioned for single-handed manipulation. For theexample of FIG. 1A, the handheld ultrasound scanning apparatus 102 iscoupled by a connector cable 111 to an ultrasound processing unit 112,which is coupled by a video cable 113 to a display unit 114. The displayunit 114 can optionally include touchscreen capability for receivinguser inputs. In other preferred embodiments, wireless communication link(e.g., bluetooth, infrared, etc.) are used to link the handheldultrasound scanning apparatus 102 with the ultrasound processing unit112 and/or to link the ultrasound processing unit 112 to the displayunit 114. In still other preferred embodiments as described furtherinfra, one or both of the ultrasound processing unit 112 and displayunit 114 are in miniaturized form and integral with the handheldultrasound scanning apparatus 102. An opening 121 is formed in casing107 across which is disposed a texturably couplant-porous material sheet122. The texturably couplant-porous material sheet 122 has an inner sidethat faces inward with respect to the casing and an outer side thatfaces outward with respect to the casing. The handheld ultrasoundscanning apparatus 102 further comprises an ultrasound transducer 124disposed within the casing 107 that contacts the inner side of thetexturably couplant-porous material sheet 122 and that mechanicallytranslates thereacross to scan the tissue volume therethrough.

For one preferred embodiment, the texturably couplant-porous materialsheet 122 comprises a taut fabric sheet having with material propertiessimilar to those described in the commonly assigned WO2007/014292A2,which is incorporated by reference herein. As used herein, fabric refersgenerally to a material structure of interconnected parts, such as canbe formed by knitting, weaving, or felting natural or synthetic fibers,assembling natural or synthetic fibers together into an interlockingarrangement, fusing thermoplastic fibers, or bonding natural orsynthetic fibers together with a cementing medium, and further refers tomaterials having similar textures or qualities as those formed thereby,such as animal membranes or other naturally occurring substances havingfabric-like properties (either inherently or by processing), and such asmaterials generated by chemical processes yielding fabric-like webbings.In one preferred embodiment, the taut fabric sheet is substantiallyinelastic. Preferably, the taut fabric sheet is sheer to allowvisibility therethrough, as may be advantageous where (a) the casing 107is optically transparent to allow visibility of the skin surfacethereunderneath, or (b) even if the casing 107 is not opticallytransparent, allowing viewing of the inner workings of the handhelddevice through the taut fabric sheet. One particularly suitable materialfor the taut fabric sheet comprises a polyester organza material havinga filament diameter of about 40 microns and a filament spacing of about500 microns. However, the taut fabric sheet may comprise any of avariety of other fabrics that are substantially inelastic and generallyporous to ultrasound couplants without departing from the scope of thepresent teachings. Examples include, but are not limited to, polyesterchiffon fabrics and cloth fabrics comprising straight weaves ofsubstantially inelastic fibers. Where the weave is particularly tight(for example, the cloth used in men's dress shirts or the cloth used inmany bed sheets), porosity can be achieved by perforating the cloth orotherwise introducing irregularities that allow the ultrasound couplantto soak or seep through.

As an alternative to a taut fabric sheet, or in combination therewith,the texturably couplant-porous material sheet 122 can comprise a ventedmembrane as described in WO2007/014292A2, supra, in which a membraneousmaterial is patterned with voids therethrough to provide porosity toacoustic couplant. Examples of materials that can be used for the ventedmembrane include, but are not limited to, polypropylene, polyester(including but not limited to Mylar), polyethylene, PTFE, PET, paper,Kevlar, metal, and epoxy-fiber composite materials. Preferably, the sizeof the voids and the average void pitch is equal to or greater than thewavelength of the acoustic signals being applied. By way of example, fora 7 MHz ultrasound frequency, the size of the voids should be about 0.5mm or greater. The vented membrane can be formed, for example, bybeginning with a uniform film sheet and establishing a void patterntherein by one of stamping, perforating, or other process designed toestablish a void pattern. Examples include laser perforation,perforation using hot needles, die cutting, cold stamping, andhot-stamping. For one preferred embodiment, the vented membranecomprises a film sheet less than 1 mm thick, with at least 25% of asurface area of the film sheet being occupied by voids. In anotherpreferred embodiment, at least 80% of the surface area is occupied byvoids. In an alternative fabrication method, the vented membrane can beformed by a vertical fusing of a first monofilamental pattern and asecond monofilamental pattern. In one example, each monofilamentalpattern can comprise 0.04 mm monofilaments having a pitch of about 0.5mm.

In comparison to the use of a material that is not couplant-porous atthe interface between the ultrasound transducer 124 and the skinsurface, the texturably couplant-porous material sheet 122 provides forhigher image quality for at least the reason that it promotesdissipation of air bubbles that might otherwise form at that surface.Notably, whereas the taut fabric sheet(s) and vented membrane(s) inWO2007/014292A2, supra, are incorporated into relatively wide-areacompressive surfaces for static wide-area dual-handed and/ormechanically supported breast stabilization, it has been found that suchtexturably couplant-porous materials can also be advantageously appliedin the context of handheld volumetric scanning in which there is aunique blend of desirable performance criteria. More particularly, whenwetted with acoustic couplant, it has been found that the texturablycouplant-porous material sheet 122 takes on a uniquely desirablecombination of slidability over the skin, on the one hand, when there isa slightly lesser downward (skinward) compressive force as the clinicianmoves the device around or toward the area of interest, and grippabilityof the skin, on the other hand, when there is a slightly greaterdownward (skinward) compressive force as the clinician holds the devicestill over a location of particular interest, as when a particularthree-dimensional subvolume is to be stabilized for high-qualityvolumetric imaging and/or for the manipulation of the biopsy needlerelative to a lesion in that subvolume.

Preferably, the texturably couplant-porous material sheet 122 is wettedwith an acoustic couplant facilitating acoustic coupling between theultrasound transducer 124 and the tissue sample. This can be achieved bypre-impregnating the texturably couplant-porous material sheet 122 priorto contact with the skin surface, applying the acoustic couplant to theskin surface prior to contact by handheld ultrasound scanning apparatus102, or both.

According to a preferred embodiment, the casing 107 comprises a housing108 that houses the ultrasound transducer 124, and a frame 110 acrosswhich the texturably couplant-porous material sheet 122 is extended. Theframe 110 is configured and dimensioned to be mateably connectable tothe housing 108, the frame 110 establishing the opening 121 of thecasing 107 when connected to the housing 108. For one preferredembodiment, the texturably couplant-porous material sheet 122 is affixedto the frame 110, and the frame 110 is removably mateable to the housing(for example, click-on and click-off) by the clinician or an assistant,whereby the frame 110 and texturably couplant-porous material sheet 122form a single disposable element than can be removed and replacedbetween patients.

Illustrated in FIG. 1B are guide rails 126 that form part of an overallelectromechanical actuation assembly (not shown) for repetitivelytranslating the ultrasound transducer 124 within the housing 108 in aback and forth manner across and in contact with the inner side of thetexturably couplant-porous material sheet 122, as indicated by thearrows pointing in the positive-x and negative-x direction in FIG. 1B.The electromechanical actuation assembly will generally include smallelectrical motors (minimotors, micromotors) mounted on the ultrasoundtransducer 124 and/or the housing 108 along with gears, belts, linearencoders, etc. as necessary to actuate the ultrasound transducer 124 inthe manner(s) described herein, usually under the control of a controlprocessor (not shown). Examples of actuation assembly technology thatmay be suitable for use in the handheld ultrasound scanning apparatus102 are described in U.S. Pat. No. 7,334,478B2 and US20070016060A1, eachof which is incorporated by reference herein. The actuation assemblytechnology may alternatively be similar to that used in certaincommercially available real-time 3D (“live 3D,” “4D”) ultrasoundscanning probes such as the Voluson 730 probe available from GeneralElectric Medical Systems.

According to one preferred embodiment, the display unit 114 displays,under the control of a display processor within the ultrasoundprocessing unit 112, a first image 116 corresponding to a first planegenerally parallel to the scan plane of the ultrasound transducer 124and passing through the target lesion L, for providing an image L′ ofthe target lesion along with an image 104′ of the biopsy instrument whenit is maintained in that plane by the clinician. The display unit 114further displays a second image 118 generally perpendicular to both thefirst plane and the texturably couplant-porous material sheet andpassing through the target lesion L for providing an image L″ of thetarget lesion, along with an image (not shown) of the biopsy instrument104, which would appear as a point object if and when it pierces thatplane. Optionally, automated needle segmentation and beamsteeringtechniques can be used to cause the biopsy instrument 104 to appear morebrightly in the displayed images, as described in the commonly assignedU.S. Pat. No. 6,524,247B2, which is incorporated by reference herein.Any of a variety of volumetric image processing and display techniques,including automated lesion segmentation and recognition, automatedbiopsy instrument segmentation and recognition, automated biopsyinstrument tracking, two-dimensional and three-dimensional projectionalgorithms, image superposition methods, predictive biopsy instrumentdisplay, and so forth can be used for optimal visual communication ofthe biopsy instrument 104 relative to the target lesion L. Examples ofsuch techniques are described in US2007/028221A1 and WO2007/130526A2,supra. Other examples are discussed in U.S. Pat. No. 6,216,029B1, U.S.Pat. No. 6,733,458B1, U.S. Pat. No. 6,764,449B2, and, each of which isincorporated by reference herein.

In one preferred embodiment, the size of the opening 121 and thetexturably couplant-porous material sheet 122 is approximately 6 cm in adirection parallel to the linear transducer array of the ultrasoundtransducer 124 (i.e., in the y-direction of FIGS. 1A-1B) and 9 cm alongthe direction of translation of the ultrasound transducer 124 (i.e., inthe x-direction of FIGS. 1A-1B), and the ultrasound transducer 124 isrepetitively translated at a rate in the range of 0.5 Hz (sweeps persecond) to 30 Hz. The ultrasound display 114 is preferably refreshed aseach sweep of the ultrasound transducer 124 acquires the most currentdata volume. A wide variety of sizes and shapes for the opening 121 andtexturably couplant-porous material sheet 122 consistent with thehandheld character of the handheld ultrasound scanning apparatus 102 arewithin the scope of the preferred embodiments, including 4 cm×4 cm, 4cm×3 cm, 4 cm×2 cm, 3 cm×3 cm, 3 cm×2 cm, and other sizes. Particularlyfor smaller-area preferred embodiments and/or preferred embodiments inwhich the translation distance is kept relative small (e.g., a fewcentimeters or less), the volumetric scanning rate (and correspondingdisplay refresh rate) can optionally be made even higher than 30 Hz.

FIGS. 2A and 2B illustrate side and front cut-away views, respectively,of the handheld ultrasound scanning device 102 during operation,including a conceptual view of the lesion L and a scan plane 202 passingthrough the lesion L. According to one preferred embodiment, apreliminary “survey,” “scout,” or “exploratory” sweep mode is providedin which the ultrasound transducer is oscillatorily swept by a largerdistance Δx_(A) (for example, 3 cm-9 cm) between a first set ofendpoints x₁ and x₂ at a relatively slow rate (e.g., between 0.5 Hz-3Hz) to image a larger volume of the tissue. This larger volume is thenprocessed perceptually by the clinician based on the user display and/orautomatically by the processing unit 112 to segment the location andshape of the lesion L. Based on this processing, a second set ofendpoints x₃ and x₄ separated by a lesser distance Δx_(B) (for example,0.5 cm-1 cm) are determined that encompass the target lesion L. Thisdetermination can be made by receiving user inputs identifying thoseendpoints and/or from the automated segmentation process. The ultrasoundtransducer is then oscillatorily swept across the lesser distance Δx_(B)between the second endpoints x₃ and x₄ at a relatively fast rate (e.g.,10 Hz or higher) to allow higher frame rates for a smaller volume of thetissue, which can be particularly useful as the tip of the biopsyinstrument 104 closes in upon the lesion L and as the biopsy samples aretaken. Preferably, the clinician or their assistant may enter overrideparameters at any chosen time to manually dictate the endpoints of theoscillatory sweeps and the scanning rate. Notably, the scanning rate canoptionally be set to zero, in which case the handheld ultrasoundscanning apparatus 102 may be operated in a manner similar to aconventional linear array transducer, albeit with the added advantagesof having the texturably couplant-porous material sheet 122 positionedbetween the transducer surface and the skin surface.

FIG. 3 illustrates a perspective view of a handheld ultrasound scanningapparatus 302 according to a preferred embodiment, comprising anultrasound transducer 324, and further comprising a casing 307configured and dimensioned for single-handed manipulation, the casing307 including a housing 308 and a removably mateable frame 310 definingan opening 321 across which is extended a texturably couplant-porousmaterial sheet 322. The housing 308 and frame 310 are configured suchthat the texturably couplant-porous material sheet 322 extends convexlyoutward with respect an inside of the casing 307. A scanning face of theultrasound transducer 324 is mechanically translatable, by swingableactuation of the ultrasound transducer 324, in the x-direction along theoutwardly convex surface of the texturably couplant-porous materialsheet 322. As an alternative to swingable actuation, the ultrasoundtransducer 324 can alternatively be translated along curved guide rails.

FIG. 4 illustrates a perspective view of a handheld ultrasound scanningapparatus 402 according to a preferred embodiment, comprising anultrasound transducer 424, and further comprising a casing 407configured and dimensioned for single-handed manipulation, the casing407 including a housing 408 and a removably mateable frame 410 definingan opening 421 across which is extended a texturably couplant-porousmaterial sheet 422. The housing 408 and frame 410 are configured suchthat the texturably couplant-porous material sheet 422 extends convexlyinward with respect an inside of the casing 407. The ultrasoundtransducer 424 is mechanically translatable along curved guide rails(not shown) in the x-direction along the inwardly concave surface of thetexturably couplant-porous material sheet 322.

FIGS. 5A and 5B illustrate side and front views, respectively, of ahandheld ultrasound scanning apparatus 502 according to a preferredembodiment. FIGS. 5C and 5D illustrate top and perspective views,respectively, of the handheld ultrasound scanning apparatus 502facilitating freehand ultrasound assisted biopsy according to apreferred embodiment. Handheld ultrasound scanning apparatus 502comprises an ultrasound transducer 524, and further comprises a casing507 configured and dimensioned for single-handed manipulation, thecasing 507 including a housing 508 and a removably mateable frame 510defining an opening 521 across which is extended a texturablycouplant-porous material sheet 522. The housing 508 has a lower end 509,an upper end 532, and a neck region 530 therebetween. The neck region530 is narrowably contoured relative to the lower end 509 and upper end532 and dimensioned such that the casing 507 is grippable at the neckregion between two fingers of the hand of the clinician, as illustratedin FIGS. 5C and 5D. Depending on their personal preference, theclinician may alternatively elect to grip the casing 507 between theirthumb and one of their fingers.

The handheld ultrasound scanning apparatus 502 of FIGS. 5A-5D cangenerally be used by either right-handed or left-handed clinicianswithout modifications between right-handed and left-handed use. Theparticular example of FIGS. 5C-5D generally corresponds to use by aleft-handed clinician, with the handheld ultrasound scanning apparatus502 being held by the right hand while the biopsy instrument 104 ismanipulated by the left hand. Generally speaking, use by right-handedclinicians (not shown) will entail holding the handheld ultrasoundscanning apparatus 502 with the left hand while manipulating the biopsyinstrument 104 with the right hand.

Handheld ultrasound scanning apparatus 502 further comprises aclamshell-style lid 534 coupled to the upper end 532 of the casing 507,the lid 534 including a display screen 536 integral therewith andpositioned thereon so as to be viewable by the clinician whileperforming the single-handed manipulation of the unit when the lid 534is in a closed position. In operation according to one preferredembodiment as illustrated in FIG. 5C, the display screen 536 displays atwo-dimensional image representative of a scene of the biopsy instrument104 and lesion L that would be perceived by a hypothetical acousticimpedance camera positioned directly above the handheld ultrasoundscanning apparatus 502 during the procedure (i.e., positioned somedistance along the negative-z axis in the coordinate system of FIG. 5and looking downward in the positive-z direction toward the scene),wherein such hypothetical acoustic impedance camera would be able to“see” acoustic impedance, rather than light, emanating from the tissuevolume of interest. Such two-dimensional can be achieved, for example,by computing a maximum intensity projection (MIP) image in thez-direction from the acquired ultrasound volume, although other imagecomposition methods including those based on automated lesion and/orneedle segmentation can be used. Alternatively or in conjunctiontherewith, the display screen 536 can be used for displaying anyparticular subsurface x-y plane or slabbed adjacent group of subsurfacex-y planes passing through or near the target lesion, or any of avariety of other useful biopsy-assisting views.

Referring now to FIG. 5D, handheld ultrasound scanning apparatus 502further comprises a display screen 538 integral with the upper end 532and a display screen 540 integral with an inner side of the lid 534 suchthat the display screens 538 and 540 are adjacently viewable by theclinician when the lid 534 is in an open position. In operationaccording to one preferred embodiment as illustrated in FIG. 5D, thedisplay screen 538 displays a first two-dimensional image analogous tothat of the display screen 536 of FIG. 5C, i.e., representative of ascene of the biopsy instrument 104 and lesion L that would be perceivedfrom a hypothetical acoustic impedance camera that is positioneddirectly above the biopsy scene. Preferably, the display screen 540displays a second two-dimensional image representative of a scene of thebiopsy instrument 104 and lesion L that would be perceived from ahypothetical acoustic impedance camera positioned some distance in thenegative-x direction relative to the lesion under biopsy and looking inthe +x direction toward the scene, which can be composited in a mannersimilar to the first two-dimensional image except along the x-directioninstead of the z-direction. The clinician can then use the first andsecond two-dimensional images, which include images L′ and L″ of thelesion, respectively, and images 504′ and 504″ of the biopsy instrument104, respectively, for real-time guidance of the biopsy instrument 104relative to the lesion. Alternatively or in conjunction therewith, thedisplay screen 538 may display any particular subsurface x-y planeincluding or slabbed adjacent group of subsurface x-y planes passingthrough or near the target lesion, while the display screen 540 maydisplay any particular y-z plane or slabbed adjacent group of y-z planespassing through or near the target lesion. Among other advantages, theclinician is not required to look away from the area of their hands toview the assistive ultrasound images during the freehandultrasound-assisted biopsy procedure.

The clamshell-style lid 534 is preferably openable and closeable in amanner similar to the lids of notebook computers, flip-phones, and soforth, and may optionally be rotatable once it has been opened, as withthe lids of certain notebook computers, so that the display 540 can facea different way. For one preferred embodiment, one or more of thedisplay screens 536, 538, and 540 can be similar to the touchscreensprovided with iPhones, BlackBerries, and similar devices to allow forcontrol inputs along with their display capabilities. For one preferredembodiment, the handheld ultrasound scanning apparatus 502 is entirelyself-contained, with an on-board power source, ultrasound beamformers,processors, and controllers such that no communication with an externalunit is required. For another preferred embodiment, the handheldultrasound scanning apparatus 502 can be partially self-contained inthat it comprises an onboard power source and is wirelessly connected toexternal processors/controllers. For still another preferred embodiment,the handheld ultrasound scanning apparatus 502 is connected by one ormore electrical and/or electrooptical cables to one or more externalunits that provide power, control, beamforming, ultrasound processing,and display processing.

FIGS. 6A and 6B illustrate side and front views, respectively, of ahandheld ultrasound scanning apparatus 602 according to a preferredembodiment. FIG. 6C illustrates top and perspective views, respectively,of the handheld ultrasound scanning apparatus 602 facilitating freehandultrasound assisted biopsy according to a preferred embodiment. Thehandheld ultrasound scanning apparatus 602 is designed to have a lookand feel reminiscent of a conventional handheld breast ultrasound lineararray probe in terms of the way it is gripped and handled by theclinician, but provides a sufficient amount of automated translation ofan ultrasound transducer 624 therewithin to enable usefulthree-dimensional imaging in a relatively narrow, slab-like region 625thereunder. For one preferred embodiment, with respect to the exemplarycoordinate system shown in FIGS. 6A-6C, the ultrasound transducer 624 istranslated back and forth along the x-axis by about 2 cm or less, suchthat the slab-like region 625 correspondingly extends in the x-directionby about 2 cm or less. The slab-like region 625 extends in the y- andz-directions in a manner similar to that of a conventional linear arrayprobe, i.e., according to the capabilities and settings of theultrasound transducer 624. For another preferred embodiment, thetranslation distance of the ultrasound transducer 624 along the x-axisis limited to about 1 cm or less, with the slab-like region 625correspondingly being limited to 1 cm or less. The handheld ultrasoundscanning apparatus 602 is particularly advantageous for use for breastbiopsy procedures in which it is known that the biopsy instrument 104will be maintained in a relatively narrow slab-like region near thelesion being biopsied. By limiting the translation distance (i.e., thephysical range in the x-direction that the ultrasound transducer 624 istranslated), the translation frequency (i.e., the number of times theultrasound transducer is translated back and forth per second) can beincreased for obtaining higher volumetric frame rates (volume refreshesper second), which is particularly useful for procedures in which thebiopsy instrument 104 might be moved around quickly. In one preferredembodiment, the translation frequency can be up to 30 translations persecond for obtaining volumetric frame rates up to 30 translations persecond when the translation distance is limited to about 1 cm.

In addition to the ultrasound transducer 624, the handheld ultrasoundscanning apparatus 602 further comprises a casing 607, the casing 607including a housing 608 and a removably mateable frame 610 defining anopening 621 across which is extended a texturably couplant-porousmaterial sheet 622. The housing 608 extends from a lower end to an upperend 632 and includes a neck region 630 formed therebetween. The casing607 is dimensioned with a relatively tall profile in the z-direction incomparison to the preferred embodiment of FIGS. 205A-5D, supra, and anarrow profile in the direction of translation of the ultrasoundtransducer 624 (i.e., narrow in the x-direction of FIGS. 6A-6C), suchthat the casing 607 is gripped and handled in a way that is morereminiscent of a conventional linear array probe.

Handheld ultrasound scanning apparatus 602 further comprises a firstdisplay screen 638 integral with the upper end 632 of the casing 607,and a clamshell-style lid 634 coupled to the upper end 632, the lid 634coming to rest against a backstop feature 608 a integral with thehousing 608 when opened, the lid 634 including a second display screen640 integral therewith. According to one preferred embodiment, the firstdisplay screen 638 extends in the y-direction by an amount commensuratewith the width of the ultrasound probe 624 in the y-direction (forexample, about 4 cm), while extending in the x-direction by an amountcommensurate with the translation distance in the x-direction (forexample, about 1 cm). For such preferred embodiment, the first displayscreen 638 thus has an aspect ratio of about 4:1. In other preferredembodiments, the aspect ratio of the first display screen 638 can berelaxed to only about 2:1 or greater.

In operation according to one preferred embodiment as illustrated inFIG. 6C, the first display screen 638 displays a first two-dimensionalimage representative of a scene of the biopsy instrument 104 and lesionL that would be perceived by a hypothetical acoustic impedance camerapositioned directly above the handheld ultrasound scanning apparatus 602during the procedure (i.e., positioned some distance along thenegative-z axis in the coordinate system of FIG. 6 and looking downwardin the positive-z direction toward the scene), wherein such hypotheticalacoustic impedance camera would be able to “see” acoustic impedance,rather than light, emanating from the tissue volume of interest. Asdescribed supra with respect to FIGS. 5C-5D, this can be achieved bycomputing a maximum intensity projection (MIP) image in the z-directionfrom the acquired ultrasound volume, although other image compositionmethods including those based on automated lesion and/or needlesegmentation can be used. Also according to a preferred embodiment, thesecond display screen 640 displays a second two-dimensional imagerepresentative of a scene of the biopsy instrument 104 and lesion L thatwould be perceived from such hypothetical acoustic impedance camera,wherein the hypothetical acoustic impedance camera is positioned somedistance in the negative-x direction relative to the lesion underbiopsy, the second two-dimensional image being composited in a mannersimilar to the first two-dimensional image except along the x-directioninstead of the z-direction. The clinician can then use the first andsecond two-dimensional images, which include images L′ and L″ of thelesion, respectively, and images 604′ and 604″ of the biopsy instrument104, respectively, for real-time guidance of the biopsy instrument 104relative to the lesion. In other preferred embodiments, by way ofexample and not by way of limitation, the first display screen 638 maydisplay any particular subsurface x-y plane or slabbed adjacent group ofsubsurface x-y planes passing through or near the target lesion, whilethe second display screen 640 may display any particular y-z plane orslabbed adjacent group of y-z planes passing through or near the targetlesion.

As used herein, the term compositing refers broadly to any of a varietyof techniques by which a three-dimensionally distributed property, suchas acoustic impedance, is processed to produce a two-dimensional imagethat is a view of that three-dimensional distribution (or “scene”) froma particular distal vantage point in space. The term composition angle,or direction of image compositing, refers to a vector direction betweenthe distal vantage point and the three dimensional distribution(“scene”). Examples of methods for compositing include three-dimensionalrendering techniques such as maximum intensity projection, minimumintensity projection, and ray casting, as well as other techniques suchas slabbing along the direction of the composition angle, and furthercan include graphically overlaying a highlighted or iconic version of anobject within the scene (such as a biopsy instrument) that was detectedeither intrinsically (such as by computer processing the volume tosegment the biopsy instrument) or extrinsically (such as by gyroscopicor magnetic location of the biopsy needle) as that object would appearfrom the distal vantage point.

By contrasting the preferred embodiment of FIG. 6C, for which thedisplay screen 640 faces approximately the same direction as thedirection of compositing (the display screen 640 faces the negative-xdirection and the MIP image displayed thereon was composited in thex-direction) with the preferred embodiment of FIG. 5D, for which thedisplay screen 540 faces differently from the direction of compositing(the display screen 540 faces the negative-y direction while the MIPimage displayed thereon was composited in the x-direction), it can beseen that the two-dimensional image on display screen 640 (FIG. 6)provides a more intuitive basis than that of display screen 540 (FIG. 5)upon which to interpret both the absolute and relative positions of thelesion and the biopsy instrument. In general, for cases in which thethree-dimensional acoustic impedance volume is processed to compute acomposited two-dimensional image therefrom, it is preferable for thecomposition angle to correspond to the physical angle of the displayscreen that is displaying that two-dimensional image on the handheldultrasound scanning device.

FIG. 7 illustrates a side view of a handheld ultrasound scanningapparatus 702 according to a preferred embodiment, which is similar tothe handheld ultrasound scanning apparatus 602 of FIG. 6, supra,including the first display screen 638 and second display screen 640,but with the addition of an angle detector 745 for detecting an angle θbetween the first display screen 638 and second display screen 640. Theangle detector 745 can implemented in any of a variety of known waysranging from a simple potentiometer coupled to a hinged joint betweenthe first display screen 638 and second display screen 640, to agyro-based, magnetically based, or optically based angle detectionscheme. The composition angle for the two-dimensional image on displayscreen 638 will remain constant at the angle of the normal vector 738 n,while the composition angle for the two-dimensional image on displayscreen 640 will be the angle of the normal vector 740 n, which will varyas the opening angle θ varies according to the desired position of theuser. Preferably, the compositing angle is varied in real time as theopening angle θ is changed by the user. A unique and spatially intuitiveviewing experience is provided, especially when the user tilts the angleθ by modest amounts in a back-and-forth manner, in which case there is areal-time parallax effect (due to the changing composition angles) thatis highly helpful in intuitively assessing the relative positions oftissue structures and the biopsy instrument position.

In an alternative preferred embodiment, an actuator (not shown) isprovided that automatically changes the angle θ by small amounts so thatthe spatially intuitive parallax effect can take place without the userthemself (or an assistant) needing to manually vary the opening angle θ.In still another alternative preferred embodiment, responsive to anoptional user control input (not shown), the physical opening angle θ iskept constant at the user-selected angle, while the compositing angle isautomatically varied in software at a relatively slow rate (e.g., 0.5Hz) between (θ−Δθ) and (θ+Δθ), where Δθ can be about 10 degrees or otheruser-selectable amount, thereby providing the spatially intuitiveparallax effect without requiring manual variation of the opening angleθ.

FIG. 8 illustrates a top view of a handheld ultrasound scanningapparatus 802 according to a preferred embodiment which is similar tothe handheld ultrasound scanning apparatus 602 of FIG. 6, supra, butwith the addition of user-slidable tabs 851 and 852 positioned alongsidethe display screen 638. (The lid 634 and backstop feature 608 a of FIG.6 are omitted from the drawing of FIG. 8 for clarity of presentation.)When the user positions the slidable tabs 851-852 in disposition “A”,the ultrasound transducer is translated between the corresponding pointsx_(1,A) and x_(2,A) in the x-direction, which are spaced apart by afirst distance Δx_(A). When the user positions the slidable tabs 851-852more closely together in disposition “B”, the ultrasound transducer istranslated between the corresponding points x_(1,B) and x_(2,B) that aremore closely spaced together. The farther-apart disposition “A” may beused for with a slower probe translation frequency (e.g., between 0.5Hz-3 Hz) as during a “scout” process where the basic beginning positionsof the biopsy instrument and lesion are established, while thecloser-together disposition “B” may be used once the user has narroweddown the specific region of interest and is desirous of a faster volumerefresh rate (e.g., between 10 Hz-30 Hz) for faster visual feedbackduring crucial manipulations of the biopsy instrument. In an alternativepreferred embodiment (not shown), the display screen 638 can be atouch-sensitive display, and the functionality of the slidable tabs851-852 realized in a controlling software applet that recognizes, forexample, two-fingers touching the screen simultaneously. If the fingersare recognized as sliding apart on the touchscreen, then Δx is increasedand the probe translation frequency is decreased, whereas if the fingersare recognized as sliding together on the touchscreen, then Δx isdecreased and the probe translation frequency is increased.

Whereas many alterations and modifications of the present invention willno doubt become apparent to a person of ordinary skill in the art afterhaving read the foregoing description, it is to be understood that theparticular embodiments shown and described by way of illustration are inno way intended to be considered limiting. By way of example, althoughthe ultrasound transducer that is mechanically translated within thehousing for at least one preferred embodiments supra is a linear arrayultrasound transducer, in other preferred embodiments it can be adifferent ultrasound transducer type such as a 1.25D, a 1.5D, or a 2Dultrasound transducer. By way of further example, although describedprimarily in terms of percutaneous biopsy of the breast, one or more ofthe above-described preferred embodiments are readily applicable and/oradaptable for compressive biopsy for the arm, the leg, the neck, theabdomen, or other human or animal body part.

By way of still further example, although described supra primarily interms of purely freehand biopsy in which the biopsy instrument isentirely separate from the handheld ultrasound scanning apparatus, inother preferred embodiments there is also provided a biopsy guide thatmechanically links the biopsy instrument to the handheld ultrasoundtransducer for increased stability, such as those described in thecommonly assigned U.S. Pat. No. 6,695,786B2, which is incorporated byreference herein.

By way of further example, although advantageous in the context offreehand ultrasound assisted biopsy procedures, one or more of theabove-described preferred embodiments is also advantageous forfacilitating certain types and portions of the breast brachytherapyprocess. Breast brachytherapy involves the insertion of a smallradioactive seed into the breast, usually at the site of a tumor thathas recently been removed, for temporary radiation treatment of thesurrounding tissue. The temporary radiation treatment is often performedin multiple sessions over the course of several days, the radioactiveseed(s) being inserted at the beginning of each session and removed atthe end of each session. Typically, a catheter-based structuralframework is formed prior to the first session to ease the process ofdelivering the radioactive seed(s) to and from the target site over thecoming sessions, and for ensuring proper separation between thedelivered seed and the surrounding tissue. In one common type of breastbrachytherapy process often called catheter-balloon brachytherapy, thecatheter-based structural framework is formed by freehand insertion of ahollow needle or other hollow applicator device (“brachytherapyapplicator device”) into the breast until its tip is near a desired siteof the seed, after which a small inflatable balloon or balloon-likeelement and a small attached catheter (“catheter-balloon assembly”) aredelivered through the lumen of the brachytherapy applicator device tothe desired site. After appropriate “inflation” with saline, the balloonor balloon-like element will serve as the seed holder during thesessions and the attached catheter will be used to deliver theradioactive seed(s) thereto and therefrom. As with percutaneous breastbiopsy procedures, there is a need to provide high-quality volumetricultrasound image guidance for the percutaneous freehand manipulation ofa generally elongate brachytherapy applicator device toward the desiredradiation site, at the same time, in view of the generally undulousnature of the breast surface, there is also a need for localstabilization of the breast subvolume that is being image. It has beenfound that the uniquely desirable combination of slidability andgrippability along the scanning surface provided by a handheldvolumetric ultrasound scanning device according to one or more of thepreferred embodiments supra is also particularly advantageous for use inultrasound guidance of a brachytherapy applicator device toward thedesired radiation site.

By way of even further example, although particularly advantageous inthe context of freehand ultrasound assisted biopsy procedures, one ormore of the above-described preferred embodiments can be advantageousemployed in any of a variety of non-biopsy related ultrasound imagingcontexts such as, but not limited to, real-time volumetric cardiacimaging and real-time volumetric fetal imaging. Therefore, reference tothe details of the embodiments are not intended to limit their scope,which is limited only by the scope of the claims set forth below.

1. An apparatus for ultrasonically scanning a tissue volume having atissue surface, comprising: a casing configured and dimensioned forsingle-handed manipulation relative to the tissue surface; a texturablycouplant-porous material sheet extending across an opening of saidcasing and having an outer side and an inner side relative thereto, theouter side for compressively contacting the tissue surface; and anultrasound transducer positioned against the inner side of thetexturably couplant-porous material sheet and being mechanicallytranslatable thereacross for volumetrically scanning the tissue volumetherethrough.
 2. The apparatus of claim 1, wherein said texturablycouplant-porous material sheet comprises a taut fabric sheet.
 3. Theapparatus of claim 2, wherein said taut fabric sheet is substantiallyinelastic and comprises a material selected from the group consistingof: polyester organza materials, polyester chiffon fabrics, and clothfabrics.
 4. The apparatus of claim 1, wherein said texturablycouplant-porous material sheet comprises at least one of a taut fabricsheet and a vented membrane.
 5. The apparatus of claim 1, wherein saidtexturably couplant-porous material sheet extends convexly outward withrespect an inside of the casing, and wherein said ultrasound transduceris mechanically translatable in at least one direction along saidoutwardly convex texturably couplant-porous material sheet.
 6. Theapparatus of claim 1, wherein said texturably couplant-porous materialsheet extends concavely inward with respect an inside of the casing, andwherein said ultrasound transducer is mechanically translatable in atleast one direction along said inwardly concave texturablycouplant-porous material sheet.
 7. The apparatus of claim 1, whereinsaid casing comprises: a housing member to which said ultrasoundtransducer is moveably attached; and a frame mateably connected to saidhousing member, said frame establishing the opening across which saidtexturably couplant-porous material sheet is extended; wherein saidtexturably couplant-porous material sheet is affixed to said frame, andwherein said frame is manually removable from said housing member,whereby said frame and texturably couplant-porous material sheet form adisposable unit than can be removed and replaced between patients. 8.The apparatus of claim 7, further comprising a transducer actuationassembly coupled to said ultrasound transducer and configured such thatsaid ultrasound transducer is mechanically translatable in a swept,oscillatory manner across said texturably couplant-porous material sheetat a rate of 0.5 Hz-30 Hz.
 9. The apparatus of claim 8, furthercomprising: a control processor for controlling said actuation assemblysuch that said ultrasound transducer is oscillatorily swept at a firstrate between a first pair of endpoints to scan a first volume withinsaid tissue volume; a first processor for processing ultrasound scandata from the ultrasound transducer to generate a volumetricrepresentation of said first volume; a display unit for displaying imageinformation derived from said volumetric representation of said firstvolume; and a second processor configured to determine a second pair ofendpoints spaced closer together than said first pair of endpoints andcorresponding to a lesion-containing subvolume of said first volume;wherein said control processor is configured, upon said determination bysaid second processor, to control said actuation assembly such that saidultrasound transducer is oscillatorily swept at a second rate betweensaid second pair of endpoints to scan said lesion-containing subvolume,wherein said second rate is higher than said first rate.
 10. Theapparatus of claim 9, wherein said determining the second pair ofendpoints comprises one of (i) receiving a user input indicative of saidsecond pair of endpoints based on the displayed image information, and(ii) automatically segmenting a lesion from said volumetricrepresentation of said first volume and establishing said second pair ofendpoints based on said segmentation.
 11. The apparatus of claim 10,wherein said first pair of endpoints are spaced apart by a firstdistance in the range of 3 cm-9 cm, and wherein said second pair ofendpoints are spaced apart by a second distance in the range of 0.5 cm-1cm.
 12. The apparatus of claim 1, further comprising a display screenfor displaying image information derived from said volumetric scans,wherein said display screen is attached to said casing and positionedthereon to be viewable by a user performing said single-handedmanipulation.
 13. The apparatus of claim 1, said casing having a lowerend near said opening, an upper end, and a neck region between saidlower and upper ends, wherein said neck region is narrowably contouredrelative to said lower and upper ends and dimensioned such that saidcasing is grippable at said neck region between one of (i) a thumb and afinger of a hand of a user, and (ii) two fingers of the hand of theuser.
 14. The apparatus of claim 13, further comprising a first displayscreen for displaying first image information derived from saidvolumetric scans, wherein said first display screen is integral withsaid casing near said upper end and positioned to be viewable by theuser performing said single-handed manipulation.
 15. The apparatus ofclaim 14, said casing further comprising a clamshell-style lid coupledthereto near said first display screen, said lid covering said firstdisplay screen in a closed position and not covering said first displayscreen in an open position, said apparatus further comprising a seconddisplay screen integral with an inner side of said lid, said seconddisplay screen being adjacently viewable with said first display screenwhen said lid is in said open position and displaying second imageinformation derived from said volumetric scans.
 16. The apparatus ofclaim 15, wherein said first image information corresponds to a firstplane within said tissue volume generally parallel to said texturablycouplant-porous material sheet, and wherein said second imageinformation corresponds to a second plane within said tissue volumegenerally perpendicular to said texturably couplant-porous materialsheet.
 17. The apparatus of claim 15, further comprising a third displayscreen integral with an upper side of said lid and displaying thirdimage information derived from said volumetric scans when said lid is insaid closed position.
 18. A method for performing a medical procedure inwhich a generally elongate freehand percutaneous medical instrument ismanipulated toward a target lesion in a tissue volume, comprising:manually maintaining a handheld ultrasound probe in compressive contactwith a surface of the tissue volume, the handheld ultrasound probecomprising a texturably couplant-porous material sheet having a firstside compressively contacting said surface and a second side oppositethe first side, the handheld ultrasound probe further comprising anultrasound transducer repetitively translated across the second side ofthe texturably couplant-porous material sheet to acquire volumetricultrasound scans of the tissue volume therethrough; viewing ultrasoundimages of said target lesion and at least a portion of the freehandpercutaneous medical instrument on an ultrasound display that is updatedin real time with said acquisition of said volumetric ultrasound scans;and guiding said freehand percutaneous medical instrument toward saidlesion based at least in part on the viewed ultrasound images.
 19. Themethod of claim 18, wherein said freehand percutaneous medicalinstrument is selected from the group consisting of: a freehand biopsyinstrument, and a freehand brachytherapy applicator device.
 20. Themethod of claim 18, wherein said texturably couplant-porous materialsheet comprises a taut fabric sheet that is substantially inelastic andcomprises a material selected from the group consisting of: polyesterorganza materials, polyester chiffon fabrics, and cloth fabrics.
 21. Themethod of claim 18, wherein said texturably couplant-porous materialsheet comprises at least one of a taut fabric sheet and a ventedmembrane.
 22. The method of claim 18, said handheld ultrasound probecomprising a casing having a lower end near said texturablycouplant-porous material sheet, an upper end, and a neck region betweensaid lower and upper ends, said neck region being narrowably contouredrelative to said lower and upper ends, wherein said manually maintainingcomprises gripping said neck region of said casing between one of (i) athumb and a finger of a hand, and (ii) two fingers of the hand.
 23. Themethod of claim 22, wherein said ultrasound display comprises a firstdisplay screen that is integral with said casing near said upper end.24. The method of claim 23, said ultrasound display further comprising asecond display screen flippably attached to said casing and having anopen position in which said second display screen is viewably adjacentto said first display screen, wherein said viewing ultrasound imagescomprises (i) viewing a first ultrasound image on said first displayscreen corresponding to a first plane within said tissue volume, and(ii) viewing a second ultrasound image on said second display screencorresponding to a second plane within said tissue volume generallyperpendicular to said first plane.
 25. A handheld volumetric ultrasoundprobe, comprising: a casing configured and dimensioned for single-handedmanipulation within which is disposed a mechanically oscillatedultrasound transducer; and a texturably couplant-porous material sheetextending across an opening of said casing for compressively contactinga tissue surface, said ultrasound transducer being mechanicallyoscillated across said texturably couplant-porous material sheet tovolumetrically scan the tissue therethrough.
 26. The ultrasound probe ofclaim 25, wherein said texturably couplant-porous material sheetcomprises a taut fabric sheet.
 27. The ultrasound probe of claim 26,wherein said taut fabric sheet is substantially inelastic and comprisesa material selected from the group consisting of: polyester organzamaterials, polyester chiffon fabrics, and cloth fabrics.
 28. Theultrasound probe of claim 25, wherein said texturably couplant-porousmaterial sheet comprises at least one of a taut fabric sheet and avented membrane.
 29. The ultrasound probe of claim 25, said casinghaving a lower end near said opening, an upper end, and a neck regionbetween said lower and upper ends, wherein said neck region isnarrowably contoured relative to said lower and upper ends anddimensioned such that said casing is grippable at said neck regionbetween one of (i) a thumb and a finger of a hand of a user, and (ii)two fingers of the hand of the user.
 30. The ultrasound probe of claim29, further comprising a first display screen for displaying first imageinformation derived from said volumetric scans, wherein said firstdisplay screen is integral with said casing near said upper end andpositioned to be viewable by the user performing said single-handedmanipulation.
 31. The ultrasound probe of claim 30, said casing furthercomprising a clamshell-style lid coupled thereto near said first displayscreen, said lid covering said first display screen in a closed positionand not covering said first display screen in an open position, saidapparatus further comprising a second display screen integral with aninner side of said lid for displaying second image information derivedfrom said volumetric scans, said second display screen being adjacentlyviewable with said first display screen when said lid is in said openposition. 32-38. (canceled)